Burning most of the other newspaper in box (8)
I believe the answer is:
itchiest
'burning most of the other newspaper in box' is the definition.
I can't judge whether this definition defines the answer.
'the other newspaper in box' is the wordplay.
'the other' becomes 'it' (old-fashioned UK slang for sex).
'newspaper' becomes 'i' (UK newspaper).
'in' is an insertion indicator.
'box' becomes 'chest' (chest is a kind of box).
'i' going within 'chest' is 'chiest'.
'it'+'chiest'='ITCHIEST'
Can you help me to learn more?
(Other definitions for itchiest that I've seen before include "Most restless" , "extremely irritating" .)